Various methods for stably performing discharge or charge of a battery pack are proposed.
Patent Document 1 (Japanese Unexamined Patent Publication No. 2003-217679) discloses the following discharge method. Whenever a battery voltage drops to a discharge termination voltage during discharge of a secondary battery, the secondary battery is intermittently discharged while repeating a temporary stop. At this time, each time discharge is restarted after a temporary stop, the discharge is performed while a discharge current is reduced in a stepwise manner. Thereby, compared to a case where high-rate discharge is performed continuously, it is considered possible to extract a large discharge amount from a secondary battery, and to stably increase the discharge amount.